Electrical motor structure



Jan. 26, 1960 w. HARGREAVES 2,922,902

ELECTRICAL MOTOR STRUCTURE Filed April 24. 1956 II l 7 3 4-3 4244 40 4l S'l'l /8 Z2 45 45 I4 TW,

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n ELECTRICAL MOTOR STRUCTURE William Hargreaves, Jenkintown, Pa., assignor, by mesne assignments, to Daystrom, Incorporated, Murray Hill, NJ., a corporation of New Ierse Application April `24, 1956, Serial No. 580,302 11 Claims. (Cl. 310-7-43) l This inventionv relates generally to electrical motor structures and more particularly it relates to an electrical motor structure and a method of assembly especially adapted fol manufacture with high standards of mechanical and electrical accuracy.

Conventional electrical motors usuallyy comprise a shell within which is supported the stator core and coils. The

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erator embodying thefimportant features of the invention shown in Figs. l and 2; and

Fig. 4 is a longitudinal cross section of the motor structure shown in Fig. 2 illustrating the structure as it would be prior to the final machining of the various external and internal diameters of the end caps and stator core.

Referring to the drawings, this invention provides an electrical motor structure comprising a conventional stator core 10 made up of annular laminations slotted to receive conventional stator coils having end portions 11 which protrude longitudinally of the core. The outer diameters of several of the end laminations of core 10 may be reduced in order to receive the end caps 12 and 14 with the shell portions 15 and 16 thereof fitting over the end laminations of core 10, as shown in Fig. 4.

It will be noted that the shell portions 15 and 16 are of greater thickness than illustrated in Fig. 2. Also, the

shell is provided with end caps having armature supporting bearings, the end caps being clamped to the shell by means of bolts extending from one cap to the other.

Present day control apparatus of certain types utilize small motors and/or motor generators which are in the category of precision instruments. Mechanically, such motors and generators must be .manufactured to high standards of precision because the electrical characteristics of such motors and generators require such precision in order to provide the electrical operating characteristics necessary to carry out the functions of the particular control circuit. Accordingly, motors and generators having the conventional mechanical design become exceedingly expensive to manufacture and exceedingly complex with respect to manufacturing techniques.

The principal object of this invention is to provide an electrical motor structure of relatively simple character and yet capable of being manufactured to high standards of mechanical and electrical accuracy.

Another object of this invention is to provide a relatively simple method of assembly for electrical motor structures of the character set forth in the preceding paragraph. y v

In accordance with this invention there is provided an electrical motor structure comprising a stator having an annular core and windings supported therein, and end caps adapted to be' mounted on and secured to said stator, said end caps including housing portions surrounding the coil` ends which protrude from the stator, thereby to permit use of fa filling or bonding material within the housing and around the coil ends which serves to lock the end caps to the stator and to form a self-supporting structure.` i

In accordance with a further feature ofthis invention,

the electrical motor structure described herein may be assembled andnished by mounting the end caps on the ends-Y of the stator, introducing a bonding material into `from' the accompanying drawings and the followingde- -scription and claims:

fFig. 1 is anhfeud elevation of the motor structure provided in accordancefwith this invention;

*'Fig. 2 is a cross section taken on line 2 2 of Fig.' l;

;;. Fig, .`3..is alongitudinalcross section of ,a motor/gen- ,Y

external and internal diameters of the end caps and the stator core are greater or less, repectively, than those shown in Fig. 2 indicating that these internal and external diameters may be machined after assembly..

End caps 12 and 14 are formed to provide annular channels 17 and 18, respectively, which are substantially larger in cross section than the cross sections of the coil ends 11, thereby creating spaces around the coil ends.

After caps 12 and .14 are mounted on the stator core the assembly, as shown in Fig. 4, may be mounted in a xture adapted to clamp the end caps to the stator core. The xture and the assembly may then be rotated about a vertical axis through the VcenterV of the assembly. A thermo-setting bonding material may then be introduced into the assembly at points such, for example, as 19. and 20, whereby centrifugal forces cause the bonding material to flow into the spaces 17 and 18 around the coil ends 11,. Simultaneously, heat may be appliedrto the entire assembly and the center of the assembly may be kept free of bonding material by providing a bleed hole 21 at the proper distance from the center of rotation of the assembly. Introduction of bondingpmaterial'may be continued until it begins to flow through the bleed hole 21 and in this manner the inside diameter .which the bonding material will occupy canbe controlled. After the bonding material is v completely cured, it forms a bonding element 22 between each c ap and each end of the core 10. The assembly as illustrated in Fig. 4 then may be removed from the spinning fixture for machine inishing. The assembly may be mounted in the lathe, for example, on its approximate longitudinal axis and the external diameters of core 10 and caps 12 and 14 may be finished down to a uniform diameter throughout the length of the assembly, as vshown in Fig. 2.

fThe same is true of the internal diameters at 23, 24, and 25 of the caps 12 and 14, and the stator core 10, respectively. p

Internal groovesvmay be machined in the end portions of caps 12 and 14 to receive snap rings 27 and 28 which serve to lock conventional ball bearings 29 and 30 within caps 12 and 14. YWashers 31 and 32 and, if desired, an extra washer 33 may be provided for accurately positioning bearings 29 and 30. From the foregoing description, it will be apparent that the bonding element 22 will serve to fasten and support the end caps 12 and 14 with respect to core 10. The end caps, in turn, serve to support the bearings 29 and 30 which, in turn, serve to support the rotor 35 and its shaft 36. By reason of the fact that all of the external and internal diameters are machined after the end caps are bonded to the core 10, the rotor 35 is positioned with extreme accuracy with respect to core 10. This is true with respect to centering of the rotor `and also with respect to longitudinal alignment of the rotor with the core. It will be noted that longitudinal alignment is controlled by the positionaszasoa Fig. 3 illustrates a modification ofthe invention;:where irl-amortir rand a generator, for eXample,fmay be assembled 'on a common shaft as a unitary structure. There may be provided a stator core 38 for a rriotor.V An end cap -as'sembly39 may be mountedonone end of this core in exactly the same manner as described in connection with'Figs. 2 and 4. l

There may also be provided a stator core 40 for -a generator having an end cap assembly 4l v'siinilarin all essential respects to end cap.12,lfo'r example, in Figs. 2 and 4, but has an inside Adiameter'sliglitlylarger than end cap 39; A Cores 38 and 40 may then be joined to one another by means ofY a cylindrical"shelleZlZwhieh surf rounisethe end eoils 43 of -meter e'r' `38Y t Yend coils 44 of generator core 40. The' entire assemblyv may then be moi-lnted in a'V likture for introduction of the bonding material `45 into the 'spaces 'snirounding'the end coils filling constituting a means of securing said caps to said core, and armature supporting bearings mounted within eachof said caps. v

5. A motor structure comprising a stator having an annular core, an end cap mounted to each end ofY said core, each end cap includingy aportion embracing and ill SpaCedLrelation. thereto and a filling ot bonding rm-V terial filling any empty space between saidhousing andY engaging one end of said core and an annular housing said core, andhvin'g a predetermined :inside diameter established by a bleed hole in 'one of said end caps, said filling constituting a means of securing sid caps to said cap mounted' on the other end ofsaid core, one of said withinthe end capsu 39 and-'H41` andV4 also ,within the cylindrical shell member 42; As'previously described in connection with the embodiment of Fig.y 4, heating and spinning the assembly produces flow of the bonding material so that the centerrof the assembly is kept free' of bonding material, centrifugal forcescausing the filling to assume aninside diameter substantially Ythat'oli the en;V

larged'inside diameter-of end cap 41: After the bonding material 45 has" been cured,l the assembly may then be machined in the same manner asr describedin jconnectionf'with lthe assemblies illustrated-in' Figs.' 2 and- 4.

- The invention claimed is: I

lrA motor structure comprising aV statonhaving an annular core and windings supported` thereon with coil ends'prot'ruding therefrom, an end cap mounted to each end of sadlcore; Yearch end capincluding'an'outer shell member Viitted` to one" end of saidr core and an annular housing l surrounding said coil VVends in spaced relation thereto,a filling Vof bonding vmaterial filling the space between said honsing and saidlfcoil ends and having Va predetermined inside 'diameter established by a bleed hole in one of said endcap's, said filling constituting a'means of securing said capsto'said core, and'armatur'e' support#r ing bearings mounted withinv each of said caps.

2;-A motorv structure comprisingr astator `having an annlar core andY windings`supported thereon' with Yc'oil ends protruding-therefrom, an'end cap mounted to each endV of said core; each YendV capi includingy a portion em-y bracing one-.end of said coreA and 'an annular Yhousing surrounding said coil ends inspaced relation thereto, and alilling' of bonding material lillingl the space between said*housing*andY saidcoil ends and having a predete're mined inside diameter established by a bleed holein one of said `rendi caps; `saidiilling constituting a" means of securing? said-caps to said corre.

caps' having an apertureof larger Vinside diameterthan that of said Vstator and a filling of bonding material filling any empty space' betweeny said housing and 'said core, said filling constituting means of secl'iri'ng said caps to said core, and having a predetermined inside diameter established 'by` 'said end cap aperture, Y l

7. A method of assembling an electrical motor having la stator with coil ends piotr'ding therefromV and end caps which include housing space for said Vcoil ends Vand bearing supportingisur'faces, comprising the steps of a stator and with coil ends protrudingrtherefrom and mounting said end caps on the end'sof lsaid stator, lling said'housing spaces to a predetermined degree with a bonding material, sirnultaneosly spinning 'said assembly and heatingv thersaine to distribute said material into said spaces, simultaneously bleeding oi any excess bonding material; cooling said material to create'a bond between said caps and said statorgrandiinally machining internal and Vexternal diameters ot aidcaps andstator.

8.'A method of assemblingarrelectricalmotor having end caps which include housing space adacent said coil ends and bearing supporting surfaces; comprising the steps of mounting said endvcaps onj thefendsk of said stator, filling said housingi spaces Ytoja predetermined degree with abonding material simultaneously by spinning said assembly to;distributev saidmaterial Vuntil` said iillinghas an inside diarnet'er deter/minedlby means for bleeding' eeess k'filling l'l'fs'ide` saidi'as'sernbly, curing said 3`. A motor structure comprising a stator"having",an`

Va'rin'ular core-and windings Ysupported thereon withwcoil ends` protruding` therefrom,A an end* capv mounted tol each endiof said core, each end capfincludin'g an-outer shell member VfittedL toL Vone endA offsaidj coreand an vannular housing surroundingv said coilr ends in spaced Vrelation thereto, and meansior securing -saidcap's'to said' corev consistingof a iilling Vofv cured thermosetting bonding material lill-ing the'sp'ace between-said" housing andV said` established" byi'a bleed hole `ini onev ofn SaidQhd caps; Said' y n lng pp orting surfaces, comi p ,off mounting end" caps'fodthejends of `s`a1d s` tor, illing'said'housin'g `spaces to a [predetermined ,'egree with a bbndin material', lsimultaneously spinning said `assembly and'lieatigthe saine'to distribute saidmaterial into said spaces, and cooling said material to cretea'b'ond. between said' caps andsaid stator.

10; A.A methd o f "assemblingnfelectriel nrofdr'having a' stator with'jcoilgendsA protruding therefromL and end caps ,which-pi' elude' housing spafr said' 4coil ends and bearing 'supporting surfaces, 'corfrip'rising'` the vsteps of mounting said endy caps on the ends ofsaid'stator, lilling' saidillosing spacesto av Vpr'edeterrninedfdegree,with a bonding lr'naterial simultaneously by spinningf'said' assembly about the axis dened by sid'statoruntil said filling has an' insidediameterv determined byv means for-bleeding excesstilling' outside said (assembly, andthen curing said inattesi-'to create' rbond between' said' capswand said sta't'.' Y

11. A method of assembling an electrical motor having stator larid endl vcaps which include vhousing-f'space' adjacent said core and "bearing supporting surfaces, conr- -prising the' stepsl of'r'nounting saidfendycapsV on the ends of.T saidfstator,"lillingsaidr housing? spacesL-witlr a bonding terial until said filling has Ian inside diameter determined by 'a central aperture in one of said caps for bleeding excess filling outside said assembly, curing said material to create a bond between said caps and said stator, and

irlally machining internal and external diameters of said caps and stator.

References Cited in the file of this patent UNITED STATES PATENTS Dills Oct. 18, 1955 

